Sud-Ouest SO 6020 Espadon

The first turbojet-powered single-seat fighter of French design to be built, the SO 6020 Espadon (Swordfish) interceptor was developed by the Societe Nationale de Constructions Aeronautiques de Sud-Ouest (SNCASO) under the design leadership of Lucien Servanty. Conceived to meet the requirements of a programme promulgated on 25 March 1946, and the subject of an order for three prototypes placed two months later, on 28 June, the SO 6020 was powered by a 2268kg Rolls-Royce Nene turbojet with, unusually, an aft-mounted ventral air intake. Proposed armament was initially to have comprised four 30mm cannon and four 12.7mm machine guns, this later being changed to six 20mm or 15mm weapons. The first prototype flew on 12 November 1948 and the second on 16 September 1949, the latter being modified, after initial test, with NACA-type lateral intakes in place of the ventral intake. It was appreciated at an early stage that the SO 6020 was underpowered and would offer inadequate performance, a major redesign as the SO 6021 therefore paralleling initial flight testing of the SO 6020. The third prototype, intended for tactical reconnaissance, was completed as the SO 6025 with lateral intakes and a ventrally-mounted SEPR 25 auxiliary rocket motor of 1500kg thrust, this flying on 28 December 1949. The second prototype, with a similar rocket motor installed in the rear fuselage, became the SO 6026, flying in this form for the first time on 28 March 1953.